Build a browser plugin compatible with Chrome and Firefox

I'm an entrepreneur and would like to get a browser plugin developed. The browser plugin should be compatible with both Firefox and Chrome browsers. In order to be successful candidate for the job application, I'll require that you build a very simple prototype plugin as a test before you get the job. For the test plugin, the instructions are below: I've attached a list of domains. When you visit one of the domains in the list, you're plugin should display an alert message saying "You've visited the domain: [login to view URL]". Additionally, when the plugin is clicked, there should be a text box containing the list of domains found in [login to view URL] and it should be possible to add or remove domains from the list. Please submit these test plugins to me and from here, I will select the winning candidate.